Seal for and method of packing joints in a glass furnace



Sept. 5, 1967 J. T ZELLERS, JR

SEAL FOR AND METHOD OF PACKING JOINTS IN A GLASS FURNACE Original FiledMarch 31, 1959 4 Sheets-Sheet l s q 6o 2 [1217 VENTOR .Lf. gamma, c.(16.6%) -e ATTORNEYS Sept. 5, 1967 J. T ZELLERS, JR

SEAL FOR AND METHOD OF PACKING JOINTS IN A GLASS FURNACE Original FiledMaroh ifil, 1959 4 Sheets-Sheet 5 INVENTOR g BY ga /mar. jelM/Lfic.

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ATTORNEYS Sept. 5, 1967 J. "r. ZELLERS, JR

SEAL FOR AND METHOD OF PACKING JOINTS IN A GLASS FURNACE 4 Sheets-Sheet4.

Original Filed March 31, 1959 INVENTOR Emma. jaw/I ge. BY

flfi egfl w -e ATTORNEYS United States Patent 3,340,031 SEAL FOR ANDMETHOD OF PACKING JOINTS IN A GLASS FURNACE James T. Zellers, Jr.,Charleston, W. Va., assignor'to Libbey-Owens-Ford Glass Company, Toledo,Ohio, a

corporation of Ohio Original application Mar. 31, 1959, Ser. No.803,220. Divided and this application Nov. 25, 1964, Ser. No. 415,854

Claims. (Cl. 65-27) This is a division of application Ser; No. 803,220,filed Mar. 31, 1959 and now abandoned.

The present invention relates broadly to the production of sheet orwindow glass, and more particularly to improved method and apparatus forproducing such glass with a minimum of distortion.

The term sheet or window glass, as used herein, is intended to meanflat, drawn glass having fire-polished surfaces attained during thesheet formation, as distinguished from plate glass, which ismechanically ground and polished, after being continuously formed as aribbon.

As is well known, commercial sheet or window glass is produced bydrawing a sheet or ribbon continuously from a pool of molten glassdirectly into final usable form, so that no subsequent surfacingtreatment is required to impart smoothness and transparency. However,one of the disadvantages of flat, drawn sheet glass has been waviness orso-called distortion in the finished product. Such distortion is due toa lack of thickness uniformity or, differently expressed, to alternatelythick and thin areas in the glass sheet. Different varieties ofdistortion are known in the art by various names which have been coinedto designate specific types. Among these are long wave' distortion,short wave distortion, hammer, batter, etc.

It is believed that these distortion defects in sheet glass are due tothe presence of non-uniform and uncontrolled conditions within'thewindow glass furnaces. More specifically, that they are due to a lack ofsufliciently uniform temperature conditions from side to side of thestream or channel of molten glass flowing toward'and into the zone ofsheet formation, and alsoto the adverse influence of thermally inducedair or convection currents that move toward, along and around thenewly-formed sheet.

Moreover, it has been actually proven that the distortion difiicultiesthat have heretofore been considered to be almost a characteristic of,as well as a necessary evil, in commercial window glass production canbe overcome by proper control of atmospheric and temperature condi-'tions within the furnace.

Therefore, it is the primary aim of this invention to substantiallyreduce, it not entirely eliminate, distortion defects in window glassand distortion problems in its production.

Another object of the invention is to accomplish the above purpose bythe provision of a novel method and apparatus for controlling airmovements within the sheet glass furnace.

Another object of the invention is to provide a glass furnace includingmeans for isolating the various chambers of the glass from one anotherand from atmospheres exterior to the furnace.

Another object of the invention isthe provision of means for controllingthe temperatures of the molten glass across the width of the furnace.

Still another object of the invention is to generally improvetemperature uniformity in window glass furnaces and to eliminatealternate hot and cold streaks, lines, spots and the like in the moltenglass.

Other objects and advantages of the invention will become more apparentduring the course of the following description, when taken in connectionwith the accompanying drawings.

In the drawings, wherein like numerals are employed to designate likeparts throughout the same:

' FIG. 1- is a fragmentary plan view of a window or sheet glassfurnaceprovided with two window glass machines;

FIG. 2 is a transverse'vertical sectional view. through one of thecooling chambers of the furnace, taken substantially along the line 2--2of FIG. 1;

FIG. 3 is a longitudinal vertical sectional view taken on line 3*-3 ofFIG. 1;

FIG. 4 is a fragmentarylongitudinal vertical sectional view taken online 44 of FIG. 1;

FIG. 5 isa transverse vertical sectional-view through one machine of thefurnace taken substantially along line 55 of FIG. 1;

FIG. '6 is a fragmentary perspective view of asealing bar employed inthe furnace; j FIG. 7 is a fragmentary cross-sectional view through onemachine of the furnace taken on line 7 7 of FIG. 3;

FIG. 8 'is an enlarged cross-sectional view of one of the lip-tiles;

' FIG. 9 is a cross-sectional detailview of the lip-tile taken on line99 of FIG. 8;

FIG. 10 is a fragmentary elevational .view of one side offthe machineshowing one end of the machine .enclosure;

FIG. 11 is a transverse vertical sectional view of the enclosure paneltaken on line 11-11 of FIG. 10;

FIG. 12 is a detail view of the mounting frame for the enclosure panels;

FIG. 13 is a fragmentary enlarged detail view of the mounting frame; and

FIG. 14 is a longitudinal sectional view'of an extension of the machineshown in FIG. 3 and of the forward end of the annealing lehr-connectedthereto:

Referring now more particularly to the drawings, and with specificreference to FIG. 1, there is illustrated a continuous sheet glassfurnace which is-designated in its entirety by the letter A. It isconventional in furnaces ofthis character generally to includea'gas-fired'regenerativetype melting tank such as shown atB whichsupplies molten glass to one or more suitable refiningor conditioningchambers; and, as here shown,'there is provided a pair of suchrefiningchambers, separated by' a crotch wall C and such as have beenillustrated at D. Although in no way restricted thereto, the presentinvention is particularly well adapted for use with a so-called Colburntype of sheet glass drawing machine and it will be described in thatconnection here. Thus, the forward end of each refining chamber D isjoined by a cooling chamber E to. a draw-pot F positioned below a'drawing chamber G (FIGS. 1 and 3). a

' In a continuous tank-furnace such as just described, a mass of glass20 is reduced to'molten consistency in the melting tank B and flows fromthe melting end into and through the refining chambers D Within which itis properly conditioned. From one or the other of the refining chambers,the molten glass'move's through the associated cooling chamber E whereit is gradually brought down toward working temperature, and finally itflows into the working receptacle or draw-pot F in the drawing chamber Gfrom which a sheet or'ribbon of glass 21 may be continuously drawn. Thedraw-pot F, in a conventional Colburn type window-glass machine, issupported upon stools 22 on thebottom 23 withinthe drawing or potchamber.

v H which is heated by gas flames from burners 24 introthoughsubstantially set in its final sheet form, is deflected into thehorizontal plane about a bending roll 26 situated in the drawing chamberG and then passes over a socalled idler or intermediate roll 27 andthrough a flattening chamber I where the said ribbon 21 is supported andcarried forwardly upon a series of horizontally aligned machine rolls28. The ribbon advances from the drawing and flattening chambers G and Jinto a lehr L (FIG. 14) wherein it is supported and carried along uponthe horizontally aligned rolls 28 until suitably annealed.

Now it has been customary, in most attempts to improve window glassdistortion, to direct corrective efforts around and particularly in thezone of actual sheet formation. While this is believed to be ofconsiderable importance, it has also been known that to achieve the bestresults, such corrective efforts preferably should be taken long beforethis.

Accordingly, it has been found that the manner of supplying batchmaterials to the furnace can be influential in setting up waves orcurrents in the molten glass which operate to disrupt the normallycontinuous flow of the molten glass into and through the refiningchambers. Likewise, the periodic reversal of the firing and consequentlythe direction of pressure of the burning gases from one side of thefurnace to the other sets up rapid fluctuations in temperature andpressure. This has been found to be especially true when the entrancefrom the refining chambers into the cooling chambers has been relativelyopen therebetween. Thus, the differentials of temperature and pressureforced back and forth in this vicinity have undoubtedly beeninstrumental in directing currents of air onto the surface of the glassand impinging the same, at irregular degrees of temperature and therebyproducing so-called cold streaks. Success in the reduction of thisundesirable condition has been obtained by the introduction of submergedbars into the molten glass at this entrance point to close the open areaabove the glass against movement of the air between the refining andcool-ing chambers. However effective as such bars have been, because oftheir inherent size and slight imperfections in their surfaces thepressures set up in the melting area and refining chambers cause aircurrents from these chambers to gain entry into the cooling chambersover and around the surfaces of the bars.

One important feature of the present invention is the provision of aremarkably effective seal for the entrance from the refining into thecooling chambers in the form of a special cut-off bar 29 partially aboveand partially below the molten glass at the entrance to the coolingchamber E. This bar which is here best seen in FIGS. 4 and 6 is ofgenerally L-shape and has an enlarged portion 30 on the upper end of thevertical leg 31 and a preferably angled ledge 32 on the upper surface ofthe horizontal leg 33. As illustrated in FIG. 4, the enlarged portion 30abuts the lower edge of the entrance arch or wall 34 and acts to provideboth an air and a liquid seal between the cooling and refining chambers.

To improve the surface-to-surface relation between the upper, enlargedportion 30 of the bar 29 and the wall 34, the upper corner 35 of thevertically disposed surface 36 is provided with a rabbeted portion 37extending horizontally thereacross and downwardly at the opposite ends38 of the bar. These ends normally carry the bar 29 bodily on the uppersurfaces of the breast walls 39 of the furnace and for this purposeproject outwardly from the body portion of the vertical leg 31 which isintended to span the channel between the side walls 40 of the refiningchamber. The bar ends 38, FIG. 6, are provided with inwardly directed,vertically disposed notches 41.

At the time the bar 29 is installed in the furnace and in closeproximity to the wall 34, the rabbeted portion 37 forms a groove or openarea which is then filled with a plugging or insulation material adaptedto substantially close off or seal the open area and thesurface-to-surface relation of the bar and the wall. A preferred mannerof forming such a seal is to pack a rope-like material having highheat-resistance characteristics into the bottom of the groove or openarea and then cover the same with a meltable glass composition, asindicated at 42 and 43 in FIG. 4. By way of example, the rope-likematerial can be an alumina silicate fiber with an organic carrier fiberincorporated therein. Another material that may be employed to equallygood advantage for such purposes is a fibrous felt product consistingsubstantially of pure quartz fibers. The covering layer 43 of meltableglass can be formed by placing waste or cullet glass in strip form orotherwise on the insulation layer 42. The insulation material as wellmay be packed into the vertically disposed areas of the rabbetedportions 37 at the bar ends 38. The advantages gained by the use of suchmaterials resides in the fact that as the cullet glass melts under thefurnace heat, it combines with the insulation materials and softens togradually fill the irregularities of the bar 29 and of the surface ofthe wall 34 thereby completely sealing the voids and otherwise openareas along the joinder of their surfaces.

Preferably, coolant pipes 44 are arranged above the bar 29 to create aslightly cooler atmosphere in the vicinity of the fill materials 42 and43. This will by suitable control of the cooling medium in the pipes 44,operate to lower the temperatures in the vicinity of the melted glassmaterial and thereby cause the same to become slightly hardened andprovide an even more effective seal. The notches 41, in the ends 38 ofthe bar 29, likewise are preferably filled with a plugging material 45,such as clay or the like, which is forced downwardly therein. Thisoperates to close the spaces between the ends of the leg portion 31 ofthe bar 29 and the adjacent surfaces of the walls 40 of the refiningchamber thereby improving the extent to which a complete sealing orclosure is produced along and between the surfaces of the furnace wallsand the bar.

This manner of sealing makes it possible to substantially nullify theadverse effects of the pressure changes in the refining chamber thatresult from the flame reversal at the regenerators. It has beendetermined that this pressure change has heretofore been largelyresponsible of streaks of cross ream as a result of alternatelyfollowing cold and hot streams of air and combustion gases from side toside of the furnace.

Because of its special shape, the bar 29 also sets up a backflow of hotglass along the ledge 32 and toward the side walls 39 or edges of therefining and cooling chambers near the glass surface which assists inestablishing more uniform glass temperature conditions across thecooling chamber. Thus, the lower extremity of the leg 31 of the bar 29produces a downward and then upward flow of molten glass as. it entersthe cooling chamber E which results in a continual surge of glass ontoand laterally along the ledge 32 of the bar. As the lateral flowlessens, the glass again flows downwardly and in so doing causes areturn flow of the cooled glass in the edge areas and in the vicinity ofthe side walls 39 of the chambers with the result that such glassbecomes subject to a rearward current which operates to return thecooled glass into the refining chamber D and toward the highertemperature molten glass in the melting zone of the furnace.

Although generally referred to as a cooling chamber, the chamber B maybe more aptly described as a heat extracting chamber since thetemperature of the glass passing through the channel area thereof isgradually lowered by the controlled radiation or dissipation of heatand, it has been found that to effectively control sheet quality, it isimportant that this be done in such a manner as to establish andmaintain a quiescent atmospheric condition above the glass surface inthis area. According to the present invention this is accomplished firstby the provision of a so-called radiant roof with means being providedto modify or balance the thermal conditions above the said roof and inopposition to the heat rising therefrom. Thus the roof arch 46 of thecooling chamber E may be formed of refractory materials known to havelow reflective and high conductive characteristics. By way of example,one such material is silicon carbide. This, or equivalent materials,have been found to be well-adapted to promote absorption of the heatfrom the air above molten glass, and to then radiate the same outwardlyin the outside atmosphere. Secondly, ingress of relatively cooler airfrom the outside must be prevented from moving inwardly along theabutting surfaces of the blocks, making up the roof or arch 46. Tothisend, these blocks may be individually rabbeted in their uppercorners whereby a grooved area will be formed when the blocks areinstalled. These grooves receive an insulation material 47 of similarsealing characteristics to that employed in connection with the sealingof the cooling chamber at the bar 29. This manner of sealing the surfacejoints of the blocks unites the blocks into a more or less solid surfacewhich is further sealed at its perimeter to the entry arch wall 34, theoutlet arch wall 48 as well as to the blocks 49 forming the uppermargins of the wall 50.

The roof arch 46 may be installed at any suitable predeterminedelevation which will of course establish the amount of air space aboutthe glass in which air turbulence must be prevented. -It is hereinproposed to mount the roof arch relatively low with reference to thesurface of the molten glass which in itself operates to create anenclosed chamber of greatly restricted volume of area. This reduced areaor air space. beneath the arch and the fact that the blocks thereof aresecured in sealed relation tends to prevent any turbulence of aircurrents and, by inducing a quiescent atmospheric condition, greatlyassists in establishing an even or equalized cooling pattern from thecenter to the sides of the glass channel.

Lowering of the roof arch also enables the installation of lower sidewalls 50 which of course increases the effectiveness of thesubstantially sealed arch and the control of the atmosphere in thechamber formed thereby. Obviously as the height of the walls 50 isincreased, more area'is created that is susceptible to the entry ofoutside air currents which in part may be influenced by barometricpressures. These may vary throughout the day to set up an unbalance inpressure conditions between the outside temperatures and that in thecooling chamber.

Since it now becomes possible to gradually cool the glass flowingthrough the channel of the cooling chamber by substantially uniformradiation of heat from the roof arch 46, a more eflicient control of thespeed of its movement can be excercised to draw a smoother, more uniformand distortion-free sheet in the drawing chamber G. And it has beenfound that by increasing the rate of glass flow through the coolingchamber, the stagnation and chilling of the glass along the sides isconsiderably reduced.

' Further, temperature uniformity 'can be achieved by insulation of theside walls 50, forming a part of the channel in which the glass moves,as is indicated at 52.

in FIG. 2'. The layers of insulation can be varied in height as well asthickness to produce a graduated manner of control along these areas.

In order to regulate the rate of heat loss from the outer-surface of thearch 46, a plurality of air ducts 53 may be arranged in parallel withone another and the longitudinal axisof the cooling chamber. These ductsareprovided with upwardly directed stacks '54, equipped with valves 55,which are connected in common to a supply manifold 56. The bottom wall67 of each duct is provided with a plurality of small openings throughwhich the air is directed downwardly toward the arch. This tends tocreate a cooling blanket of air'into which the radiated heat from thearch of the cooling chamber chines, it has been a common practice toprovide gas' rises. Consequently, by modifying the amounts of air fromthe ducts 53 andtransversely across the width of the arch 46, the rateof heat loss can be controlled to the end that the side areas of theglass normally cooling and forming in and along the sides of the channelwill actually be reacted upon the slower loss of heat from the sidemargins of the arch disposed thereabove. And this will permit a desiredamount of balanced cooling to be carried out in the central area of themolten glass wherein a higher temperature is normally found.

Accordingly, by sealing the entry area and the arch of the coolingchamber, in addition to the insulation of the side walls thereof, arelatively stable condition of air can be maintained in the coolingchamber which greatly assists in reducing the formation of streaks ofrelatively cool glass even in areas of normally high temperature.Likewise, by controlling the rate of heat loss, a more balancedcondition of cooling in the central surface area of the molten glass canbe obtained which will result in a more equalized thermal condition between the said central surface area and the side areas thereof. Thethermal conditioning of the glass in the cooling chamber can beindicated and so more accurately controlled by the use of thermocouplessuch as are indicated at '58 in FIGS. land 3. These instruments may bearranged in suitably spaced relation in the longitudinal axis of thechannel and laterally thereacross. And while being-herein shown asinstalled in the bottom 59, it will be apparent that thethermocouplescan be mounted in other areas of the chamber to equally good advantage.

-The cumulative effect of the improved manner of sealing andconstructing the glass furnace that have been thus far described is todeliver the molten glass to the draw-pot F properly conditioned, free ofdefects, and at a relatively high uniform temperature of a degreecompatible with the thickness and speed at which the glass sheet orribbon 21 is to be drawn.

In order to further reduce the formation of any lines or cordiness inthe glass'sheet, as herein shown, the conditioning of the molten glassin the cooling chamber is also controlled by providing a bar or dam inthe immediate upper surface of the flowing glass. In this way, particlesof eroded refractory material that are carried along in the'glass streamare halted on one side of the bar and consequently do not find their wayinto the actual drawing area. For this purpose, a tube of quartz havingclosed ends is located in the surface of the glass as shown in FIGS. 2,3 and 4, and supported at its ends by brackets 61"supported on the sidewalls of the cooling chamber. It appears after successive tests, thatthe quartz tube does not collect the particles so as to graduallyacquire an encrusted, dirty surface, but to the contrary merely impedesthe progress of such particles until they become further reduced in thehot glass stream and are carried along as an intimate part thereof.

As best shown in FIGS. 3, 5 and 7, the drawing chamber G is separatedfrom thecooling chamber E by the outlet arch wall 48, by oppositelydisposed side walls 62 and by the roof 63. The bottom of the drawingchamber G is partially separated from the working receptacle F by afront lip-tile, generally designatedby the numeral 64, and a rearlip-tile 65 which define, between their opposed surfaces 66 and 67, theactual zone of sheet formation as the glass is drawn upwardly from theworking receptacle or draw-pot F and over the bending roll 26 in thedrawing or forming chamberG.

In the operation of the so-called Colburn typema burners as sources ofheat beneath the front lip-tile. These, however, in themain, have provento be sources of dirt, due in part to the products of combustion anduncontrolled air currents which result in contamination of the air spaceabove the molten glass and in the sheet drawing area. As illustratedhere, an enclosed heating structure is substituted for the customaryfront lip-tile.

and has not only given all of the advantages of the open fire burnersbut also a noticeable improvement in absence of dust and dirt anddiminution of air currents in the relatively thin and restricted passbeneath the lip-tile. The improved structure is embodied here in amuffle having a heat radiating surface directed downwardly toward theglass surface. By employing such a radiant surface across this area, itis possible to either introduce heat at desired areas and/or to createan atmosphere conducive to the withdrawal of heat.

Additionally, when the central area of the molten glass flowing beneaththe lip-tile is running hotter than the edges, it may be found that thelower temperatures in the edges are more compatible to the speed of thedrawing operation and the thickness of the sheet to be produced. In thiscase, cooling air can be directed toward the central area of theimproved hollow or muffle lip-tile and will be radiated therethroughtoward the central area of the molten glass to reduce the temperaturetherein.

Such a mufile-form of lip-tile 64 as shown in FIGS. 8 and 9, is formedof a basic elongated refractory block 68 having a downwardly directedU-shaped channel 69 formed therein. The oppositely disposed side Walls70 of the channel are provided with outwardly directed grooves 71 whichserve to carry outwardly directed flanges 72 of a closure panel 73. Thepanel is substantially U-shaped in inverted relation to the form of theblock 68 and the web 74 spans and closes the open mouth of the channel69. This panel is made up of the same or a like material as the roofarch 46 and consequently is adapted to radiate heat therethrough. Thelip-tile 64, as indicated in FIG. 9, is located at each of its ends inclosely abutting relation to the inner surfaces of the side walls 62.

More particularly, a clamp plate 75 is located on the inner, uppersurface of the channel 69 while a substantially tubular beam 76 isdisposed in aligned relation on the upper surface of block 68. At spacedpoints between the ends of the beam, the block and the plate, alignedholes are provided to receive bolts 77 that are initially passed throughmounting brackets 78 and then threaded at their ends into the plate 75.The mufiie lip-tile 64 may thus be supported in the drawing chamber G bymeans of a bar 79 passed through the several brackets 78 and carried atits externally located ends by any suitable type of bracket or othersupporting means.

It now becomes apparent that when heating burners are inserted throughopenings 80 provided in the side walls 62, the closed passageway 81 ofthe block 68 will conduct the heat therefrom onto the panel 73 which byreason of its radiant properties will transfer the heat to the air spaceabove the glass and thus reduce any tendency to cooling or stagnation inthe sides of the pool. Since each end of the lip-tile is incommunication with the outside atmosphere through the openings 80, theproducts of combustion and any residual dirt or dust will be isolatedfrom the atmosphere within the drawing chamber.

Opposite to the lip-tile 64 and in the area of the rear wall 82 of thedraw-pot, the drawing chamber G is further sealed against the ingress ofany waste gases resulting from the pot burners 24. By reference to FIGS.3, and 7, it will be seen that the hot combustion gases from suchburners circulate throughout the area confined within the enclosurewalls 25 and rise upwardly about the working receptacle or draw-pot F.Thus the side walls 83 of the pot are structurally connectedsubstantially in sealing relation to the adjacent wall 25 by cap blocks84 while the rear pot wall 82 is equipped with a partition 85. Thispartition is preferably made up of interlocking sections of asubstantially inverted T-shape, with the web 86 of the T forming a basecarried by the top surface of wall 82.

The vertically disposed leg 87 of the T-shaped partition is directedtoward the undersurface of the rear lip-tile 65. In order to produce atightly sealed relation therebetween,

the present invention contemplates a groove 88, formed in the undersurface 89 of the tile, filled with the sealing insulation maerial 90.Alternatively, the insulation material may be of a mat formation adaptedto be laid upon the upper edge of the leg 87 and compressed thereuponwhen the lipe-tile 65 is installed in its functional position. Thisinsulation may be an alumina silicate fiber with an organic carryingfiber incorporated therein, or like packing material that can be easilyplaced upon the vertically disposed leg 87 of the partition or packedinto the groove 88.

The vertical leg or wall 87 of the partition is also preferably made asthin as practicable, without lessening of its structural strength, totransmit radiantly as much heat as possible into the space beneath thelip-tile 65 at its forward end and onto the surface of the molten glassin the draw-pot. As viewed in FIG. 3, the upper area of the pot chamberas thus defined by the rear wall 82 of the draw-pot F, the partition 85and the upper ends of the adjoining enclosure walls 25 is accordinglysealed from the area of the drawing chamber G and the waste gases fromthe burners 24 can be withdrawn through passageways 91 in the bottomwall or fioor 92 of the flattening chamber and which are connected to asuitable duct 93 leading to a conventional exhaust or stack system (notshown).

' Now as the glass is drawn upwardly as the continuous sheet or ribbon21 from the draw-pot, its surfaces are normally adversely atfected bythe air currents in the forming chamber. The directions followed by suchair currents have heretofore originated from several sources and theresultant turbulency of air in and around the sheet has had undesirableresults upon sheet formation and has presented a continual problem. Toillustrate, in employing the so-called Colburn method of drawing sheetglass, the provision of several coolers has seemed advisable to controlthe gradient of temperature in the rising sheet and as it approaches thebending roll 26. Thus, these types of furnaces or the drawing chamberthereof, have been customarily equipped with sheet coolers 94,positioned adjacent the facing surfaces 66 and 67 of the lip-tiles 64and 65 respectively, and in the vicinity of the knurl rolls 95. Each ofthese devices, as in the case of the bending roll per se, has requiredmountings and/or connections to coolant sources which are located in orproject through the opposite side walls 62 of the drawing chamber. Inorder to manipulate and adjust the several mountings, prior proposedmachine enclosures have been built to contain such necessary mountingsand connections. Consequently, the supporting means as for the bendingroll 26, as shown in FIG. 5, has included the driving members as well asthe outwardly leading pipes to the coolant source. By enclosing theseseveral connections and mountings in areas in proximity to the glasssheet, there has been a constant source on each side of the furnace forcolder air currents to originate in and along the enclosures and to movelaterally inside toward the central area of the chamber. This isespecially true on the socalled operat-ors side of the furnace since inorder to make adjustments from time to time, the enclosure on this sideis necessarily opened to gain access and the inrush of colder airaccordingly has increased the cooling draft effect. In encountering thehotter air rising from the working receptacle, the currents of colderair, as indicated by the directional arrows in FIG. 5, mingle therewithbut the temperature of the rising columns of air rising against thesheet surfaces is greatly reduced from that of a desired degree ofworking temperature.

The present invention provides a much more effective means for enclosingthe drawing area of the machine to materially reduce the formation ofcircuitously moving air currents in the area of sheet formation. Asillustrated in FIGS. 3, 5 and 10 to 13 inclusive, these improved machineenclosures, generally designated by the numeral 96, are substantiallyflush" with the inner surfaces of the side walls 62 and consequently donot project outwardly into the relatively colder outside atmospheres. Inbeing so positioned, the enclosures exclude the usual cooler and rollmountings and coolant connections. This importantly removes from withinthe confines of the drawing chamber the bodily colder mountings andconnections, the dirt accumulating about the bending roll driving meansand the many openings heretofore required.

A preferred construction of enclosure, as shown in somewhat enlargeddetail in FIGS. and 11, will be seen to include a plurality of panels97, 98, 99 and 100, and a mounting frame 101 therefor. The frame 101 isstructurally attached, as by bolting, to the surfaces of openingsprovide-d in the side walls 62 and includes a sill or base plate 102 andupwardly disposed side members 103 and 104. A bar 105 interconnectingthe side members at their upper ends completes each frame. Each sidemember is provided with an angle 106 having an inwardly directed flange107. The flange 107 is adapted to receive the associated ends or edgesof the panels which combine to effectively seal the wall openings.

The panels 97, 98, 99 and 100 may be of differing or like dimensions andare made up in a laminated arrangement of sheet metal and insulationplies. Such a laminate may comprise an inwardly directed metal surface108 (FIG. 11) of steel or iron while the outer metal surface 109 may beof a more reflective metal such as aluminum. Between these inner andoutwardly disposed surfaces are contained alternate layers 110 of, asfor example, asbestos sheets and aluminum foil, that are containedwithin a panel frame 111 and secured by suitable rivets as indicated at112.

As illustrated best in FIG. 10, the several panels are formed in varyingmanners according to their relative positions. In this figure it will beapparent that several of the associated devices, as for example thelip-tiles, are shown in broken line for purposes of clarity. Thus, thelower panel 97 is formed to provide entry slots 113 for receiving theoutwardlyextending pipes for the sheet coolers 94 and an enlarged,centrally disposed aperture 114 through which the driving shafts for theknurls 95 are inserted. These openings 113 and 114 can be, andpreferably are, sealingly closed by means of blocks 115 of a laminatedconstruction, FIG. 11, similar to the panels themselves. Additionally,the panel 97 is equipped with a viewing window 116.

The nextpanel 98 is provided with a viewing window 117, the glass 118thereof being supported in an inclined plane to enable easy observationof the sheet meniscus and/or operation of the knurl rolls at anelevation slightly above the .sigh obtained through window 116. Panel99, disposed next above as shown, is provided along its upper edge witha semi-circular notch 119. This notch co-acts with a like notch 120 inthe lower edge of top panel 100 to form a suitable opening through whichthe bending roll passes. Panels 99 and 100 are both additionallyprovided with viewing windows 121 and 122, respectively, whereby acontinuous observation of the forming sheet can be obtained from thefoot or meniscus to that portion of the sheet passing around the roll26.

The several panels are mounted in the frame 101 in relatively fixedpositions by means of screw actuated clamps, generally designated 123.Each clamp has a body portion provided with a slot 124 in which theoutwardly directed edges 125 of the side frame members 103 and 104 willbe received. In order to mount the clamps on these side members, theedges thereof are provided with bayonet slots 126 (FIG. 13) which areadapted to receive a locking pin 127 secured in the clamp body andmedially passing through the slot 124 formed therein. By inward anddownwardly directed movements of the pin 127 relative to the slot 126,the edge 125 will be received within the slot 124 and the clamp bodilymounted on the frame 103 or 104.

The clamp is likewise provided with an internally threaded lug 128 inwhich is rotatably carried a threaded clamping member 129. This memberis provided with a handle 130 at one or its outer end and with a freelyrotatable, annular plate 131 at its opposite end. Preferably, each panelis engaged by at least two clamping members 129 along the verticallydisposed ends thereof. Accordingly, when the .clamps are turnedinwardly, the annular plates 131 of each will bear against the outersurface of the associated panel to urge the same firmly againstthe legor flange 107 of the angle attached to the mounting frame. Toeffectively form a seal therebetween, the marginal edges of each panelare equipped with a folded strip of heat-resistant material 132 (FIG.12) which operates to compressingly close the spaces or areas otherwiseoccurring between the metal surfaces of the frame and the respectivepanels. Of course, upon outward movement of the threaded members 129,the plates 131 will be removed from an associated panel and after whichthe clamps can be bodily removed by withdrawal of the pins 127 from thebayonet slots 126. This will afford a relatively easy means for gainingaccess to the drawing chamber and likewise will insure that the areas ofthe openings in the side walls 62 will be sealed in a substantiallycomplete manner during normal operations of the furnace.

Consequently, the surfaces of the molten glass and of the rising sheetin the drawing area will be protected from the sources of cooler air andthe resulting adverse air currents heretofore believed to be necessaryevils in production of sheet glass, particularly within the drawingchamber.

This special insulating enclosure which maintains the atmosphere of theforming area at optimum working conditions of temperature and quiescencecan be further improved by the provision of a special radiating roof orceiling in the area above the bending roll where an additionaldissipation of heat may be found desirable. For this purpose, the roof63 is formed by a series of interlocking panels or unitary plates 133 ofa thickness and metallic composition that will provide a preferentialdegree of heat radiation. The capacity of the plate 133 to transfer heatcan be readily controlled by the addition or removal of insulationprovided, if desired, on the upwardly, exposed surface thereof. Byaffording a more positive control of heat loss in particularly thedrawing chamber, the extraction of heat from the vicinity of the bendingroll operates to reduce the normally heated condition and thereby aidsthe coolants usually introduced into the hollow body thereof. This actsto reduce the occurrence of sheen on the ribbon surface which otherwisemight develop as the glass ribbon passes over the roll and is deflectedinto the horizontal plane of its continued movement.

While herein shown as equipped with a stack or plurality ofstacks 134equally spaced transversely of the chamber,,it has been found that undercertain circumstances of operation, the same can be dispensed with or'the valves therein retained in closed position. However, the stacks 134can also be used to advantage when it becomes desirable to ascertain thetemperature of the glass ribbon as it is moving over the bending rollbecause they permit suitable inspection or temperature recording devicesto be mounted in or inserted therethrough.

To isolate the newly-formed surfaces of the sheet as it passes over thebending roll 26. from air currents originating in the flattening chamberand the lehr, a partition 135 supported on the upper surface of the rearlip-tile 60 and having a vertically disposed wall 136 situated in closerelation to the intermediate roll 27 can be employed. A stack 137 (FIG.14) in the roof 138 of the flattening chamber and lehr also assists incontrolling air movement.

In reviewing the several features of this invention, it will be seenthat the improved form of sealing bar and the manner of itssubstantially closed surface relation to the walls of the furnacerefining chamber will more effectively reduce, if not completelyeliminate, the objectionable entry of prevalent air currents into thecooling chamber. This has been found to effectively correct one of theimportant sources of temperature variation in the molten glass as it isconditioned before entering the working receptacle or draw-pot. Thesealing of the roof arch of the cooling chamber has been found to morepositively maintain a stabilized air condition above the molten glasswith a resultant improvement in the turbulency of air heretoforeencountered and to greatly minimize laterally varying hot and coolerareas in the molten glass surface.

The employment of a tubular dam near the entrance of the cooling chamberhas improved the quality of the drawn glass sheet since the smallparticles of refractory materials previously found to cause lines andseeds are interrupted in their movement with the molten glass. Moreover,this tubular member does not accumulate these particles for subsequentremoval, but instead acts to subject them to the reducing influence ofthe moving glass until they further disintegrate and finally re-enterthe molten mass as an imperceptible portion thereof.

Accordingly, a molten glass of better characteristics progressivelyenters the Working receptacle and moves toward the meniscus of theupwardly drawn sheet. Now final efforts to procurring a sheet of goodoptical quality must be exerted on the molten glass or on the sheet asit approaches the bending roll. These efforts are largely confined tothe equalizing of the glass temperature across the molten pool; theobtention of a temperature at which the speed of drawing will produce asheet of given thickness and the maintenance of a suitably staticcondition of the air above the draw-pot and within the drawing chamber.By the provision of a mufile-type of front liptile, the thermalinfluencing of the glass can be carried out in a preferential manner ofoperation and with the possibility that the central area of the pool canbe as beneficially reduced in temperature as the edge portions can beraised. This accomplishes not only an improved accuracy of heatapplication in desired areas but produces this without the entry of thewaste products of burned gases of air into the air actually above theglass. These waste products due to variances in temperature and area ofentry in the drawing zone have heretofore been responsible for settingup turbulent air currents at the meniscus of the sheet and across theupwardly moving surfaces thereof. More particularly, these turbulent aircurrents have risen in the vicinity of the surfaces of the sheet and inencountering further air currents in the drawing chamber have reacted toincrease the turbulency therein. Also, by the further improvement in themanner of enclosing the drawing chamber, the further sources for theentry of cooler air, the creation of objectionable rising and descendingcurrents has been greatly reduced. With the elimination of exposedsources of heating and cooling from above the surface of the moltenglass as it enters the draw-pot together with the more stable conditionof the air within the actual area of the drawing chamber, the drawing ofa glass sheet of notably improved quality has been achieved.

It is to be understood that the form of the invention herewith shown anddescribed is to be taken as a preferred embodiment of the same, but thatvarious changes in the shape, size and arrangement of parts may beresorted to without departing from the spirit of the invention or thescope of the subjoined claims.

I claim:

1. A method of sealing a joint in a glass furnace structure comprising,packing a heat-resistant fibrous material along said joint, melting abody of glass onto and across the packed fibrous material, and thencooling said melted glass to substantially solidify the same into asealing layer.

2. A method of sealing a joint in a glass furnace subjected to hightemperatures comprising, packing a fibrous, high heat resistant materialinto the joint, and melting onto the fibrous material a layer ofmeltable glass composition.

3. A method of sealing a joint in a glass furnace as claimed in claim 2,including the step of cooling the melting glass composition whilesubjecting said joint to high temperature to substantially solidify saidmelted glass layer.

4. A seal for joints in a glass furnace subjected to high temperaturescomprising, a fibrous, high heat resistant material positioned withinthe joint, a layer of meltable glass composition over the fibrousmaterial, and means for cooling said meltable glass composition tosubstantially solidify the same while said joint is being subjected tosaid high temperature.

5. A seal for joints in a glass furnace subjected to high temperaturesas claimed in claim 4, wherein said cooling means includes a coolantpipe adjacent the seal, and means for circulating a heat absorbingmedium through said coolant pipe to remove heat from the meltable glasscomposition.

References Cited UNITED STATES PATENTS 1,754,912 4/1930 Slick -3471,838,530 12/1931 Coleman 65347 2,693,668 11/1954 Slayter 6536 X2,952,231 9/1960 Chyle et al. 6536 X 2,968,083 l/l961 Lentz et al 6527 X3,155,567 11/1964 Harr 16l170 3,157,562 11/1964 Kine et al 16117O3,278,282 10/1966 Jaray 651 DONALL H. SYLVESTER, Primary Examiner.

S. LEON BASHORE, Examiner.

D. CRUPAIN, G. R. MYERS, Assistant Examiners,

1. A METHOD OF SEALING A JOINT IN A GLASS FURANCE STRUCTURE COMPRISINGPACKING A HEAT-RESISTANT FIBROUS MATERIAL ALONG SAID, JOINT, MELTING ABODY OF GLASS ONTO AND ACROSS THE PACKED FIBROUS MATERIAL, AND THENCOOLING SAID METLED GLASS TO SUBSTANTIALLY SOLIDIFY THE SAME INTO ASEALING LAYER.